We have carried out a multidisciplinary study on the neurobiological bases of aging in the aged rat. Behavioral studies include: analysis of learning and memory, behavioral habituation and recovery of function after brain injury. Cellular studies are being carried out at a number of levels in an attempt to discover the underlying bases of behavior changes. We are examining the properties of protein synthesis, levels of hormones and transmitter receptors, and regeneration of new neuronal circuitry after cell loss.